Permafrost thawing caused by the China-Russia Crude oil pipeline based on multi-type data and its impacts on geomorphological reshaping and water erosion.

• Multi-type data characterized the disturbance of the China–Russia Crude Oil Pipeline (CRCOP) on the permafrost environment. • Mapped the development of the talik around pipelines under the influence of multiple factors. • Permafrost thawing along the CRCOP caused topographic reshaping and the regular distribution of ponds. • Synergistic changes of underground permafrost and surface features. Engineering activities in permafrost regions have a major impact on the local permafrost environment. The construction and operation of the China-Russia Crude Oil Pipeline (CRCOP) have changed the surface conditions and the soil's thermal state. However, the response of the permafrost environment to CRCOP is less studied. This article carries out ground temperature monitoring, ground surface deformation (GSD) and pipeline deformation observations, electrical resistivity tomography (ERT) measurements, and unmanned aerial vehicle (UAV) surveys to study permafrost thawing, talik development, topographic change, and pond distribution. The results indicated that the oil temperature has increased yearly and the permafrost around the pipeline has degraded quickly. The artificial permafrost table has decreased at a rate of 0.68 m/a at a location 2 m away from the center of the pipeline, and reached −11.4 m deep by 2022. The talik around CRCOP I was larger than that around CRCOP II and the two taliks were gradually approaching each other. Permafrost-thawing-induced pipeline subsidence and surface settlement have led to thermokarst depressions and water accumulation. The sinking rates of CRCOP I and II are approximately 0.2 m/a and 0.45 m/a, respectively. The ground surface settlement rate on the right-of-way of the pipeline (on-ROW) is about 5.49 cm/a. Settlement rate in ponding areas is 8.18 cm/a, significantly larger than 4.81 cm/a in non-ponding areas. The ponding area on-ROW accounts for 67.4 % and it on CRCOP I is larger than that on CRCOP II. Pipeline construction, high oil temperature, and permafrost thawing have led to the development of geohazards, which have potential to be worsen under the influence of fires, climate warming, and human activities. Multi-type data provides ground verification for satellite images to extract deformation and ponding information along pipelines, and provides a scientific basis for assessing the thermal impact of pipelines and geohazard development. [ABSTRACT FROM AUTHOR]